The Car and the Problem
Car: 1981 924 Turbo S2, US spec. Car's been in the family since sometime in '82 as my parents bought it instead of waiting for an NA 944 (good choice in my opinion) and spent what they had saved for their honeymoon on the car. Since then it's been in the Porsche Parade, auto-crossed in Old County Stadium's parking lot, and my dad spun out in the turn 5 sand trap at Road America. To say there's some nostalgia with this car is an understatement; heck I got taken to kindergarten in the back seat! Fast forward a few years (decades) and as the car was for some reason promised to my elder sister conditional upon her graduation from college, she chose instead to have my parents sell it to use the funds for her wedding. Yeah I wasn't going to have any of that. If anyone was going to buy the car it was going to be me, so I promptly did.

My parents rarely if ever drove it in the rain, it was always kept covered in their garage when not in use, waxed yearly and all around kept in good shape.

Right after I bought it in spring of 2015, we were driving it back from where we store it for winter and my dad and I noticed a wonderful mysterious ticking noise coming from the engine. Got home, opened the hood, and listened. Both of us came to the same conclusion that it was valvetrain related but it sounded funny and came and went. Figuring that it wasn't serious, right there we decided to make a project of it. Pull the head, get it rebuilt, new head gasket, throw it back together and voila! It would be fun they said! It wouldn't be that hard they said! It won't take that long they said! They, they were so so wrong...

Started the next day by dropping the exhaust, started taking ancillaries off of the car, and draining fluids and figured that the turbo, exhaust and head could all come off without pulling the engine.

Let me tell you, it wasn't fun and it wasn't easy. Exhaust came off all right, turbine housing bolts were a bit tricky but all came off, wastegate was simple but the turbo triangle flange, oh man, not fun at all. Took a good part of 3 days to figure out how to get the turbo off the manifold and the 4 bolts connecting the turbo to the block as none of them are easy to get to, all were seized on and rusted. Once the turbo was sort of off it was then decided that the next easiest course of action would be to pull the exhaust manifold and turbo at the same time. Also, not fun at all. At least 3 of the studs sheared when taking the nuts off, one stud was stuck in the head, and 2 nuts had to be cut off of the exhaust once the head and exhaust was out. Oh did I forget to mention? We ended up just pulling the head with the exhaust still attached. That's how much of a pain it was so if you are going to pull the exhaust or turbo, just pull the entire engine out of the car first. Once the head was off, our true problem was quickly discovered.

At this point the original plan's scope was FUBAR because as you can quite obviously see, piston 1 was toast. Complete, charred, carbonized, toast. The entire lower left corner of piston 1 was so damaged by detonation you could almost stick your finger down and touch the first piston ring. Even naive me knew it wasn't supposed to look like that.

Over the course of the spring and early summer of 2015 I completely stripped the engine down to the bare block. Every item that came off was labeled, most were photographed and every nut, bolt, washer, and every other piece of hardware went into a labeled Ziploc bag. (Did anyone ever tell you engineers are OCD?)

Once it was stripped it was clear that all 4 pistons were shot, most of the hoses were showing plenty of signs of wear, belts were old and starting to crack, passenger side engine mount spring was broken in two, intake elbows were cracked, and best of all, there was oil sitting in the bottom of the turbo out pipe. While I was tearing the engine apart by day, by night I started researching anything and everything about 931's; failure modes, weaknesses, piston options, rod options, turbos, you name it, I looked into it, If you ever posted something on this forum, I probably read it and I'm not even kidding.

From the start of my research there were about three options I was looking into. First, simply rebuilding this engine with new/upgraded components; 2. sell the car get a 944/951; and 3, LS1 swap. After countless late nights of research, emails, and phone calls, I decided on simply rebuilding this engine for a multitude of reasons. One I wanted to keep it mostly stock to preserve the car as is because of how great of condition it was in, but kind of a restomod/ use newer technology to make the car more reliable. Two, the car's been in the family for 30+ years so selling it broken just wasn't going to happen, at all, ever. Three, while an LS1 swap is possible on a 931, it's much more worth it to buy a broken 944 and do it there. Four, I really wanted to do a full engine teardown and rebuild as I never actually had done one before; I've had plenty of experience doing minor engine work and SAE Baja builds, but never a full car engine. Five, at the time I was nine months removed from engineering school with a damn good job and a huge wad of cash burning a hole in my pocket.

Plan goals:
-Completely tear down the engine and inspect everything for damage and wear (done already at this point)
-Replace all worn and damaged components with new, upgraded "modern day equivalent" wherever possible and stock where ever else.
-New pistons that hopefully have better detonation resistance
-Improve engine cooling via larger radiator, more coolant, as well as add an intercooler for the turbo
-Replace the stock turbo with aftermarket 951 style water cooled turbo
-Make custom exhaust manifold to bolt to new turbo
-Up the CR from 8.0 to 8.5 for better low end power
-Replace clutch and pressure plate
-Daily drivable, designed for street use, maybe an occasional track day at most
-End goal of 200-225bhp.

Step one of the rebuild was the block. I already had the entire thing torn apart so I needed to have the bores measured to see what I would have to bored out to, find new pistons, rod bolts, and bearings. First up was the bores so I gave my mechanic a call and had him come over to inspect everything. Well he started with measuring cylinder #1 and immediately started laughing, which with him, is never a good sign. Cylinder #1 was out of round by a whopping .015" which meant I would have to have the block bored to the second over size, 87mm. This in hindsight was good because it's a nice round number which makes for easy access to piston rings. My mechanic suggested a guy he knew out of Port Washington to do the machining and short block install; Speed Performance Research.

After talking with both of them, digging around online and here on the forms, I decided on custom JE forged pistons with an 8.5CR dish, ceramic coated tops, moly coated sides and weight reduction groves. At the time, Dan was in the process of moving Ideola's to Illinois so my options for rods / rod bolts was limited. Original thought was to reuse the stock rods, but as I could not get new bolts for them, I decided on light weight Pauter rods. I ended up getting them though the same shop that I was getting the pistons though so they were able to have the rods and pistons both made for 22mm wrist pins. What was quite helpful was that they were able to put a little package together for me with the pistons, rings, wrist pins, rods, locks, and rod bearings all in a cute little box of awesomeness, When I first pulled one of the pistons out I think I cried. Rods were built to handle 150hp each and with the 22mm wrist pins and high quality pistons the block should easily be able to support 600hp, aka well over double what I was actually going to run. Safety factors are your friends.

By the time I got the pistons and rods and had Jeff at Speed Performance Research start on the block, Ideola's was back online so I was able to get a set of King OS main bearings. Jeff had to grind down the crank due to it being out of round and was at a loss trying to find OS bearings for the car. Once those were in hand, the entire block machining and install process went quite smooth, albeit 2 months behind schedule.

What's interesting that happened though is somewhere down the line something got slightly screwed up. When I got the block back from Jeff assembled, the pistons were actually over the deck by about .008" at TDC, even though he took only .003" off the deck! The Crank is stock, the rods and pistons both have inspection sheets with them so I know they are in spec, so how did my pistons end up being higher than stock by almost .030"? Rerunning the compression calculations with the .066" Cometic gasket gave be a compression of 9.1CR. Not terrible, but not according to plan. All that affected really was the max boost I could run and I planned on taking it easy on boost anyways to prevent detonation. Easy enough to fix with a slightly thicker head gasket, but I figured I would get her running first, and then worry about that latter if I had to do any engine out service.

Cylinder head was in pretty good shape but by the time I was ready to get it to SPR for a teardown and rebuild; Ideola's was again back online and my options became significantly more elaborate.

I dropped the cylinder head off with the parts a few weeks after the block in order to have everything completed at the same time. Once Jeff was able to pull it apart, all the internals were fine; seats, guides, valves themselves, but due to the detonation on cyl 1, he had to weld and regrind around the valve recess. Also, the Manley shims did not work with the solid lifters due to the cam grind and other factors. Jeff had to have a custom set fabricated that were way taller than expected and an odd size.

Once I had the block and cylinder head back it was time to start bolting things together. First was the freshly rebuilt oil pump onto the block, oil pick-up, oil pan and then the new water pump. Once the bottom end was together, cylinder head was next. Between the head and the block went the Cometic .066" MLS head gasket and bolted together held together by ARP head studs. Both via Ideola's Garage. Again, might as well replace the stock basic components with better parts. Also with the possibility of putting in a thicker gasket at a later time to fix my compression issue, getting the reusable studs and nuts made more sense than the one time use bolts. Plus nuts with a 12 point pattern are much easier to deal with then the 12mm or whatever it is hex that comes on the stock bolts. When putting the cylinder head on, make sure none of your pistons are at top dead center, IF the cam is installed. If you're not careful and have the pistons at TDC, you could bend one of the valves as this car is in fact an interference engine!

After the head was on the block, most of the extra ancillaries also went on, oil filter adaptor, triangular intake support plate, engine supports, and other various do dads. From there, it was time to put the engine back in the car for everyone's favorite time, turbo time! Yes I left off the flywheel and clutch, I simply supported the back of the engine with some blocks of wood to get it at the correct height. Dan also has the Vibratecinic engine mounts which are a much higher quality mount than what comes stock with the car. Not to mention they get rid of the spring that is in the passenger side mount that failed on me.

Turbo time:
So as we all know, the K26 that comes on the 931 isn't the greatest of turbos. It's only oil cooled, the US spec version wastegate is set to 6psi, mine was already rebuilt once, and during disassembly, there was oil in the cold side out to intake pipe. My main criteria for the turbo was that it had to fit in the stock location, be water cooled, more efficient and obviously not be 35 years old. Other than that I really didn't care if it was internal waste gate or external, ball bearing or roller, brand, model or anything. Also going in I knew that bolting a new turbo to the stock manifold just wasn't going to happen, so flange style did not matter.

After dozens of more hours of digging on here, other sites, and who knows where else, I ended up picking Borg Warner's EFR series and specifically the 6258. For one, to meet my requirement of improving reliability; its water cooled, ball bearing and 30+ years newer in technology than the K26. I ended up with the internal wastegate version which would make the exhaust manifold simpler, but made install more difficult due to space. Now that I have it done and installed, I honestly would recommend going with an external wastegate if you are going to go with an EFR. Getting it to fit with the internal wastegate was more difficult than expected and piping in a EWG would be much simpler in my opinion. Also, the 6258's IGR can just barely handle the flow from a 2L with the boost levels I was planning on running. The external would give you more range.

I first got the idea for the EFR from one of WEASEL149's posts a while ago when he was looking at them and between what he said and Borg's super awesome turbo Match Bot program, I settled on the 6258. I again knew right off the bat that I would have to make a new exhaust manifold regardless of what turbo I went with due to the weird triangle flange Porsche used as well as the fact that my manifold was cracked. The 6258 is also similar in size to the stock turbos in compressor and exducer size but with much more potential boost range; so it's pretty much the new age version of the K26! Ok not really but whatever. With the other upgrades I was already planning I stuck with the stock, mid-level, wastegate canister as I was immediately going to run 10psi. Based upon what I found in match bot I could easily run 13psi with no issues but that was before my compression ratio issue came up.

Before I even ordered the turbo, I dug around on Borg's site and found some really poorly done dimensional drawings for it, scaled it up, and then made a close replica of it out of Styrofoam for fitment testing. I really didn't want to have to make any custom engine mounts or have to move anything so making sure it would fit before I spent an exorbitant amount of money on it was paramount.

Once I established that it would indeed fit, I ordered it immediately, obviously, because turbo!! By that point I already had a fair amount of the exhaust design figured out so that wasn't too much of a concern. What ended up being way more of a pain was linking the turbo's 3mm BOV (recirculation valve) port to that massive 15mm port on the bottom of the intake runner for cylinder #1. I think I ended up ordering 4 or 5 different parts from Summit to try and get a series of adaptors to work to downsize to 3mm vacuum line.

Oil Out:
So this ended up being kind of crazy and I want to redo it, but it works for now. Talk about daisy chains from hell but allowed me to use the stock oil air separator and return.
-3/8npt swivel to 8AN EAR-923108ERL (Summit)
-Vibrant Performance 8AN extender: VPE-10587 (Summit)
-12AN to 8AN reducer EAR-9892128ERL (Summit)
-12AN to 30x1.5mm RUS-670200 (Summit)
-Used stock oil air separator with minor modifications

Exhaust:
So obviously with the new turbo the stock manifold was useless. For one the turbo's internal wastegate made the WG port on the manifold pointless and it would need to be plugged, the manifolds odd 3 bolt design wouldn't mate with the EFR's T25 flange, and the stock manifold was cracked. Me being the crazy engineer that I am decided that it would be awesome to make an equal length manifold for the turbo, but after dozens of revisions and countless 3D printed pipes, I came to the conclusion that if you want the turbo to remain in the stock position, there is no way to make an equal length manifold fit with the IWG Borg. Maybe if you go external and change the location or angle a bit you could, but I couldn't get it to work.

In general though for turbo applications, it's infinitely more vital for the exhaust to reach the turbo as quickly as possible, with the fewest number of direction changes (smooth direction changes) in order to keep the exhaust temperatures as high as possible and moving as fast as possible when they reach the turbine. Does an equal length header give some advantage? Of course it does, I'm not arguing otherwise. But does it give enough of a benefit to make it worth trying to get it to fit? In my opinion? No. An equal length manifold must be tuned in both length and diameter so that the exhaust pulses help "build" on each other to provide benefit and don't cancel each other out. The issue is though that even if done correctly, it will only provide a benefit at a certain RPM range! Most people who do go this route purposefully tune it so that the pulse benefit hits right between max torque and max HP to give the biggest gain, but as I had no idea where those points would be, it wasn't even really worth it to try.

Even though the 6258 comes with a T25 flange (single port), I designed the manifold to behave more like a twin scroll. Cylinders 1 and 4 meet before the merge and cylinder 2 and 3 meet before the merge. The benefit of this design is that it eliminates the stock manifold issue where cylinders 2-3-4 flow forward, and 1 flows sort of backwards into 2-3-4. Then with the odd pipe leading to the wastegate, this leads to sub-optimal exhaust flow. Is the stock log terrible?]? Eh not really, but could it be better? Absolutely.

One of my friends was able to 3D scan the stock manifold into a STP file which I was able to take and reverse engineer the head flange and had it EDM wire cut out of 1/4" 304SS. Pipes were all 321 stainless and the turbo flange was also 304 stainless. Same friend who scanned the stock one is also an excellent welder, and due to our experience making SAE Baja frames together, we fabricated the entire thing ourselves in about 2 weeks. Don't ask me to make another one. New manifold is quite small and has short runners which give the best response possible while not having any tight bends to keep the air speed and friction as low as possible. The whole manifold was then secured to the head with ARP exhaust studs. Some may say the ARP's aren't worth the price, but if you use proper nickel based anti-seize, you shouldn't have any issues. Most of not all issues with stainless exhaust studs is user error during install or improper anti-seize.

The turbo is then bolted to the manifold via ARP studs as well, other than one corner where the ARP nut would not fit between the turbine housing and flange which is a common problem with the smallest of the EFR turbine housings. I just ended up using a grade 10.1 bolt and a regular 8mm nut. Turbo is also supported directly to the block using the stock 4 bolt holes that the K26 uses. I simply cut two pieces of 6061 aluminum and welded them together which then bolts to the block, and two of the alignment holes on the back side of the compressor housing. Not the fanciest of solutions, but it will do the trick nicely to not have the entire turbo hanging off of the manifold.

We also fabricated a new down pipe for the turbo to meet up with the stock exhaust system as I didn't want to replace the entire thing. We cut the stock exhaust about 3" in front of the CAT and replaced the section from the turbo to CAT with 3" 304 stainless and welded in a bung for a wideband AFR sensor. Summit Racing also has a handy 3" OD to 2.5" OD 304 Stainless reducer which we used to go down in size to meet up with the CAT in pipe that is 60mm (2.36"). At both the turbo out and just in front of the reducer, we installed 3" V band clamps for easy install and removal of the downpipe as compared to the stock turbine studs and nuts.

Along with the block and cyl head, I also had Jeff inspect and cleanup the flywheel. He resurfaced it and with the short block assembly rebalanced the entire thing. Finding replacements for the bolts was almost impossible due to the odd thread size vs. pitch so I just went for it and got the ARP flywheel bolts from Dan. For the clutch, due to added power of unknown proportions, I went with the SPEC stage 2+ clutch kit. Of the few reviews I saw for it, they all stated that its drivable on the street and I have to wholeheartedly agree. Honestly, it's the best feeling clutch i have ever had in any car period!

While I had the entire car apart, Dan suggested that I not only replace both the primary and secondary clutch cylinders but I should also install the 951 clutch firewall reinforcement plate. Both of the cylinders went on quite easily but the primary's nuts are a bit hard to get to. Take your time and don't rush. The reinforcement plate however, dear lord it was single handedly the WORST thing I had to do to the car. I rather pull the engine to do a spark plug replacement then do that again. Every aspect of putting it in was a nightmare. Drilling the holes in the right spot, getting the damn thing in there, getting the bolts started from inside the car, upside down with 18" of ratchet extension and 2, yes TWO swivels. I'm willing to bet there are at least half a dozen nuts and screws between my carpet and the floorboard. The step by step instructions for the install are great so I'm not going to go into detail, but it was a total PITA.

With the new turbo picked that had a water cooled housing, I needed to somehow get water to it. My two options were to T-off the 3/4" line coming off of the radiator cold side and have one run to the turbo, and the other going to the reservoir return, or add another fitting to the radiator. I decided to add another nipple fitting to the cold tank and made it 1/2" because that was the fitting size that would work with the water banjos I found that fit on the turbo. In hindsight I would recommend simply T-ing off the 3/4" fitting that is already there as you don't need to have someone punch a hole and weld in a new fitting in the radiator.

At the same time I had the fitting added I had the entire radiator recored at HD radiator in Butler WI. They were able to use the stock brackets and side tanks, and actually slightly stretched the tanks to get a thicker (~1/8") radiator core in. That may not seem like a lot but it's a 5-10% increase in core volume.

Seeing as the turbo also had a water out, that needed to obviously go somewhere. Easiest solution was to get the 951 reservoir tank and remove the stock one which also allowed for the plumbing and mount for the TMCC pump. Reservoir tank went in easy and also adds quite a bit of volume to the total water system for more added cooling capability. Additionally with the turbo sucking water from the cold side of the rad, and pumping into the tank, the turbo will always be getting water that is flowing through the radiator. The 951 setup has the turbo taking water from the radiator cold side reservoir return line, and pumping back into the reservoir, Now, could this eventually lead to issues where the water cooling the turbo is too cold? Yes and that's partially why the 951 had a temperature control solenoid built into the cooling system for the turbo to turn it on and off based upon the water temperature.

All of the water lines to and from the reservoir, radiator, turbo, water pump, rear of the cylinder head, and everywhere else were all replaced with vibrant performance radiator hose and new hose clamps. Let me tell you, the Vibrant performance hoses are worth it. They are extremely well built, can also handle oil, and are quite flexible for their size.

Intercooler
Lastly for cooling related things, I splurged and bought one of Dan's Custom TMCC's that Bell Intercooler makes and holy hell does it make a difference. I had some issues when I first put it in (user error) and having water slowly leak out to the point the pump wouldn't circulate, and you can tell just from the car's performance when it's full and circulating and when it is not. Install was relatively straightforward but just be careful as you push it onto the throttle body, make sure to lube up around where the two meet to make it slip on easier. The stock set of hoses and fittings that come with worked just fine even with the Borg turbo that they were never meant to hook up too. I put the pump where the stock 931 reservoir tank mount use to go with a simple aluminum bracket with the outlet facing downwards under the engine. The radiator for the intercooler went on the driver side where the horns are normally mounted. Horns I then moved to be inside the front bumper with a custom aluminum bracket and simply fit the bracket around the drivers side bumper shaft. Both horn wire's needed to be extended by about 10" or so in order to reach the new location. Radiator was mounted using a small aluminum bracket on each side. I had to cut two of the mounting tabs off of the rad to make it fit but it should work just fine. Also, make sure to put Teflon tape on ALL of the treads for the TMCC fittings at both the rad as well as the IC. The system is kind of hard to fill so go slow. What helped me was making sure that the water had a steep downward path to follow, first through the IC, then to the rad. Once you have a bit of water in the system, turn the pump on as that will help to pull the water though the rest of the hose. The pump DOES need to be primed in order to work though; it won't pull water up itself so you will need at least enough water in the system to reach the pump. One issue with the TMCC install though was that that the 2.25" silicone hose does NOT meet up well with the Borg as it has a 2" cold side out. You really need to get a 45 degree silicone hose with an inlet on one side of 2.25" and 2" on the other. However that's only if you are using the Borg with the TMCC, stock turbo you will be fine with what is in the TMCC install kit.

Also made improvements to the oil system. With the new turbo, the stock lines to the oil radiator would not fit and I could not find fittings that would work with the stock oil filter,so I had to come up with something new. I ended up finding some nice 10AN banjos that were meant for 18mm threads so I was able to use the stock oil filter flange, and ran 10AN hose up to the new radiator. The one I bought was about 10% or so larger in core size for some added cooling capability.

As of now I'm running the stock airbox and air filter but to fit around the TMCC pump, I had to cut the snout off of the air box. It's still mounted to the fuel distributor, but is not mounted to anything on the drivers side and just kind of sits on the hoses. Probably not the most optimal of solutions but once I go EFI the whole stock system can go as well. From the fuel distributor down to the turbo I used the stock upper rubber tube, a 2.5" OD by 3" long aluminum pipe extender, and then a 2.5" OD 90 degree bend silicone hose to meet up with the turbo cold side in. I would recommend getting a different silicone adaptor to go between the aluminum coupler and the fuel distributor if you are planning on using the stock intake system. The fuel distributor out is really more along the lines of 2-2.25" and does not meet up well with the coupler.

The intake itself was simply stripped down completely to nothing, cleaned, and reassembled with all new vacuum lines, Tee's, a few new elbows, clamps and fresh paint on all the rusted brackets. I have a ton of photos of the process on my photobucket if you need to see it in various stages of disassembly/reassembly.

Other various upgrades:
As mentioned before I installed a wideband AFR gage at the recommendation of pretty much everyone. Not only can the car run without an O2 sensor completely as it is only used for emissions, but having the gage saved me a tow truck call the first time I took it out for a drive.

I also installed a new alternator, I had the starter motor rebuilt and put in a new battery as well. All the hardware on the engine is new other than maybe 3 bolts, all pullies, brackets, mounts and pipes were all stripped of paint/ rust and repainted.

All in all the project took 18 months from start to finish and finish I just barely did. My goal was to have it done in time for the 92fourty party and it honestly took until the night before to get it running. She's now in storage for the miserable Wisconsin winter but I was able to get almost 1000 miles on the OD before the snow started to fall. How do the upgrades feel? Holy schmolly batman! It's like a whole new car. She goes like the dickens, easily feels like 200bhp and I'm only running 10psi at the moment!

Future plans include going EFI to get rid of the stock CIS system and non engine related I'm planning on doing a 951 brake system swap so I can run brembos. I'm hoping to get some dyno time this spring but that will most likely be after the EFI goes on so I won't have any really good before and after runs to compare.

All in all I'm extremely happy with how the car came out and in large part I have all of you on the board to thank for the posts and insights already on this forum and hope that this post adds to it.

_________________"931 EFR" 81 931 S2 w/ EFR 6258 turbo

Last edited by lildude4life on Wed Mar 29, 2017 1:59 am; edited 2 times in total

Tyler is being somewhat modest in describing the heroic efforts that went into that last week before 92Forty.

I was there for the first fire on Wed 22 Sep 2017. We had it going by 9 PM that evening, but then hit a near-showstopper during the warmup. Tyler and his crew thrashed all day on Thursday, and we finally got word late on Thursday evening that he'd be making the maiden voyage to 924Forty the next morning. I know his parents were thrilled to be the "just in case" chase car for the 90 minute drive down from Milwaukee, to not only see the car arrive in style, but to be one of the first arrivals!

I still haven't gotten my first drive in it, but one of these Fourth Fridays soon, we're hoping for some comparo runs...

I wouldnt go bananas in the power department without a knock sensor, I cant recommend it enough. But if you go for a good EFI system that should be incorporated.

Any recommendations on Knock sensors? I know Dan used knock sense but said he had mixed feelings on how well it worked. Not sure if the EFI kit has a knock sensor included or not.

Ideola wrote:

Tyler is being somewhat modest in describing the heroic efforts that went into that last week before 92Forty.

I was there for the first fire on Wed 22 Sep 2017. We had it going by 9 PM that evening, but then hit a near-showstopper during the warmup. Tyler and his crew thrashed all day on Thursday, and we finally got word late on Thursday evening that he'd be making the maiden voyage to 924Forty the next morning. I know his parents were thrilled to be the "just in case" chase car for the 90 minute drive down from Milwaukee, to not only see the car arrive in style, but to be one of the first arrivals!

I still haven't gotten my first drive in it, but one of these Fourth Fridays soon, we're hoping for some comparo runs...

I could write another post this long just describing the week leading up to 92forty hahaha

I don't see any reason why she wont be at the April 4th Friday. _________________"931 EFR" 81 931 S2 w/ EFR 6258 turbo

I wouldnt go bananas in the power department without a knock sensor, I cant recommend it enough. But if you go for a good EFI system that should be incorporated.

Any recommendations on Knock sensors? I know Dan used knock sense but said he had mixed feelings on how well it worked. Not sure if the EFI kit has a knock sensor included or not.

Ideola wrote:

Tyler is being somewhat modest in describing the heroic efforts that went into that last week before 92Forty.

I was there for the first fire on Wed 22 Sep 2017. We had it going by 9 PM that evening, but then hit a near-showstopper during the warmup. Tyler and his crew thrashed all day on Thursday, and we finally got word late on Thursday evening that he'd be making the maiden voyage to 924Forty the next morning. I know his parents were thrilled to be the "just in case" chase car for the 90 minute drive down from Milwaukee, to not only see the car arrive in style, but to be one of the first arrivals!

I still haven't gotten my first drive in it, but one of these Fourth Fridays soon, we're hoping for some comparo runs...

I could write another post this long just describing the week leading up to 92forty hahaha

I don't see any reason why she wont be at the April 4th Friday.

Personally I wouldnt bother with EFI if it didnt have proper boost and knock detection. Should be mandatory in this day and age for an aftermarket ECU

I have a std Bosch knock sensor placed in the empty threaded hole under the intake manifold. Its mated to a turbo XS knocklite which serverd me very well, saved my day when WUR boost enrichment and ignition module started to give me trouble. I dont think its for sale anymore, and I will swap it out for a JS safeguard that i found 2nd hand for a nice price to get active knock retard. Whenever i find the time, doesnt seems to happen nowdays...

Steve(carrerraRSR) runs a phormula knock warner, maybe he could add some words about it.

Active Knock control is very complicated, OEMs put a lot of effort to do it right. An aftermarket system should be used as a safety net for saving your engine when knock occur, which in my case works very well, not something you run into frequently imho, then you should rethink your engine calibration._________________┤80 924 Turbo